Book: # 3

THE PROCEDURE:

 Draw one of the end balls sideways about eight inches, then release the ball.  The raised ball falls in an arc towards the stationary ball and collides with it.  After the collision, both balls travel in a pendulum fashion to the end of their trajectories, then reverse their motions and collide again with each other.  After the second collision, the velocities of the balls are equal to the initial velocities.  The ball that was originally moving is now traveling with its initial velocity and the ball that was originally stationary is stationary again.  The cycle repeats itself.